Eval Plugin: different exception rendering than doctest

[Profpatsch]

Your environment

Output of haskell-language-server --probe-tools or haskell-language-server-wrapper --probe-tools:

> haskell-language-server --probe-tools
haskell-language-server version: 1.4.0.0 (GHC: 8.10.7) (PATH: /nix/store/2sxjf20hy89835gxa07a80hqsg25aywq-haskell-language-server-1.4.0.0/bin/haskell-language-server)
Tool versions found on the $PATH
cabal:		3.6.0.0
stack:		Not found
ghc:		8.10.7

Which OS do you use:

nixos
Which lsp-client do you use:

vscode
Describe your project (alternative: link to the project):

https://hackage.haskell.org/package/error
Contents of hie.yaml:
none

Steps to reproduce

Use the eval plugin to evaluate a throwing bit of code, and then run doctests on the repo, which will complain that it comes to a different conclusion because the error formatting is different:

src/Data/Error.hs:195: failure in expression `unwrapIOError $ Left (newError "oh no!")'
expected: oh no!
 but got: *** Exception: oh no!

that is the eval plugin produced expected: oh no!, but doctests will produce *** Exception: oh no! and thus report an error when running.

The solution might be as easy as adding *** Exception: to the beginning of every displayException string.